Process of endforming a tubular assembly

ABSTRACT

A method for endforming a tubular member for use assembly for a hydraulic system comprises (1) a connector member having an inner surface exhibiting a stepped configuration and a fixing member at the distal end thereof, and (2) an endform tubular member having an outer surface corresponding to the inner surface of the connector member, wherein the endform tubular member mates with inner surface of the connector member to provide an endform tubular assembly having an improved design for conveying fluids in a hydraulic system. The endform tubular assembly has inherent features therein that are measured to provide quantified values for assessing the robustness of the assembly and predict the performance of such assembly in high pressure applications for prolonged periods of time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fluid flow assemblies and, inparticular, to tubular assemblies for pressurized fluid flow. Moreparticularly, the present invention relates to a process of endforming afluid flow assembly possessing reliable features for assessing therobustness of the fluid flow assemblies in an automotive power steeringsystem.

2. Discussion of Related Art

Fluid flow assemblies for power steering systems include a steering gearhousing, a steering gear disposed in the steering gear housing, a pumpfor moving the power steering fluid under pressure, a supply line fortransporting pressurized fluid from the pump to the steering gear, and areturn line for transporting the fluid from the steering gear back tothe pump. Typically, such assemblies include one or more brackets orsupport members that are used to mount the power steering componentswithin an automotive vehicle. The end of each of the supply line and thereturn line may be individually connection to an inlet port and anoutlet port in the housing, respectively, by employing means such as a“tube-o” connector wherein a threaded nut is used behind each of thetube-o connectors to secure each of the tubes to a correspondingthreaded port in the housing. Tube-o connectors are considered to beinefficient since they require a separate installation step for eachconnection.

Other assemblies have been developed wherein a bracket is used tosimultaneously couple a fluid supply line and a fluid return line in afluid flow assembly using a single fastener wherein the completeassembly is connected to a housing with the torque of the singlefastener. While the single torque bracket connection is effective forreducing the number of operational steps necessary in the assemblingprocess, such connections are unsatisfactory because they generallyrequire that at least one of the tubular members be brazed into amachined connector. Brazed connections are not reliable, particularly inapplications where the brazed part is subjected to the harshenvironmental conditions present in the engine compartment of anautomotive vehicle. For example, the brazed part may be subjected toextremely cold temperatures in winter during periods when the automotivevehicle is not operating and then suddenly required to withstand hightemperatures during operation of the automotive vehicle. Constantvibrational episodes and occasional debris entering the compartment alsoseverely reduce the life expectancy of such brazed connections. Anotherdisadvantage of prior brazed clamp plate connections is that the clampplate does not sit flush against the housing, such that when torque isapplied to the fastener, the bracket may distort leading to prematureo-ring failure.

U.S. Pat. No. 7,032,500 describes a fluid flow assembly for a powersteering system wherein both a pressure line assembly and a fluid returnline are simultaneously connected to a steering gear using a bracketrequiring a single fastener. The bracket includes an aperture throughwhich the high pressure line extends and a notch configured to receive areturn line assembly. The return line assembly includes a connectormember to which the line is brazed or welded. The connector member alsoincludes a pair of circumferential flanges, which allows the bracket toswing over the connector member such that the hose assembly is securedto the bracket member between the pair of circumferential flanges. Insuch arrangement, the connector is compressed into the port to create aseal The high pressure tube is deformed to create a first bead and,after the high pressure tube is inserted through the bracket, a secondbead is formed to secure the tube to the bracket. Such arrangements arenot without disadvantages. For example, such fluid flow assembly mayemploy undesirable brazing or welding for securing at least one of thesupply hose and the return hose to the connector. Also two separatesteps are needed to form the two beads on either side of the bracket forsecuring the non-brazed high pressure line to the bracket. Sucharrangement is not only time consuming and labor intensive, but the tubemay be susceptible to undesirable axial rotation as well as up/down andside to side movement in the bracket. Such undesirable movement severelylimits the life expectancy of the assembly Furthermore, each of thereturn and pressure hoses require the additional step of forming agroove in the ends of the hoses for receiving an o-ring.Consequentially, current tubular assembly design does not provide aneconomical fluid flow bundle having assured long term dependability andstructural integrity, nor does it provide inherent features, which allowthe reliable assessment of the robustness of such fluid flow assemblies.

Therefore, it would be desirable to provide a method of endforming atubular assembly that would having a robust design exhibiting improvedsealability, long term dependability and reduced manufacturing costs,and which would have inherent computable quality control features forassessing the robustness of the endform tubular assembly and forpredicting the performance of the endform tubular assembly in highpressure applications for prolonged periods of time.

3. Related Applications The contents of copending applications U.S. Ser.No. ______, (Docket 07-01) and U.S. Ser. No. ______, (Docket 07-03),both relating to the same subject matter as the present application, andboth of which are filed simultaneously herewith, are incorporated hereinby reference thereto.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for endforming atubular assembly having improved sealing characteristics.

It is another object of the invention to provide a fluid flow assemblyutilizing the endform tubular assembly having improved sealingcharacteristics.

It is yet another object of the invention to provide a method forendforming a tubular assembly having measurable structural elements fordetermining the robustness of the endform tubular assembly.

It is yet another object of the invention to provide a method forendforming a tubular assembly such that the endform tubular assembly hasmeasurable structural elements for predicting the performance of theendform tubular assembly in high pressure applications for prolongedperiods of time.

The present invention provides a method for endforming a tubularassembly that is particularly useful in a fluid, flow assembly forconveying fluid in a hydraulic system such as a power steering system.Typically, a fluid flow bundle includes first and second tubularassemblies each disposed between a pump and a power steering housing inthe hydraulic system. The first tubular assembly provides pressurizedfluid from the pump to the power steering housing and the second tubularassembly returns fluid from the power steering housing to the pump. Thefluid flow assembly further includes a clamp plate configured forsimultaneously connecting the first endform assembly and the secondtubular assembly to the housing using a single torque on a fastener.

The endform tubular assembly of the present invention includes aconnector member and an endform tubular member wherein the outer surfaceof the endform tubular member corresponds to the inner surface of theconnector member so that the endform tubular member mates with theconnector member and is securely integrated therewith. Typically, theconnector member is a machined connector member having an outer surfaceand an inner tubular surface extending the longitudinal length of theconnector member. More particularly, the connector includes a firstshoulder portion defining a distal end of the connector member, thefirst shoulder portion including at least one fixing member integralwith the distal end of the first shoulder portion; (ii) a secondshoulder portion defining a proximal end of the connector member; and(iii) a brim or flange portion formed on the connector memberintermediate the first and second shoulder portions such that the brimor flange extends perpendicularly with respect to the outer surfaces ofthe first and second shoulders.

The endform tubular member has an inner surface and outer surface, theouter surface corresponding to the inner surface of the connector membersecurely locking the endform tubular member to the connector member. Theendform tubular member includes a bead uniformly formedcircumferentially around the outer surface of the endform tubular memberadjacent the distal end of the first shoulder portion of the connectormember. The bead fixedly engages the fixing member(s) in the firstshoulder portion to prevent axial rotation of the endform tubular memberrelative to the first shoulder portion, and to further preventlongitudinal movement of the endform tubular member relative to thefirst shoulder portion. The bead also provides a first unique andimportant feature in the endform tubular assembly of the invention. Aprecise measurement of the diameter of the bead provides a quantifiablevalue for assessing the robustness of the endform tubular assembly andfor predicting the performance of the endform tubular assembly in highpressure applications over prolonged periods of time.

The endform tubular assembly of the present invention is a robust designthat is designed to eliminate failure modes associated with brazingand/or welding that can cause reduced operating life of the assembly;prevent structural deformation of the clamp plate during use; andprevent premature o-ring failure commonly found in conventionalfluid-conveying tubular assemblies.

A particular advantage of the endform tubular assembly design of thepresent invention is that the assembly includes at least two inherentfeatures that can be measured independently and the quantifiable valuesobtained can be used individually or in combination to assess therobustness of the endform tubular assembly, and predict the performanceprobability of the endform tubular assembly in high pressureapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a conventional power steering assemblyas described in the prior art;

FIG. 2 is a sectional view of a portion of a tubular assembly inaccordance with of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of a connector member inaccordance with the present invention;

FIG. 4 is a cross-sectional view of an endform tubular assembly inaccordance with the invention;

FIG. 5 is a diagrammatic view of a hydraulic housing illustrating a portinto which the endform tubular assembly of FIG. 4 is inserted; and

FIG. 6 is a plane view of a clamp plate including an endform tubularassembly press fit together in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

In a first embodiment of the invention, there is described a method forendforming a tubular member. The endform tubular member exhibits ahighly robust design exhibiting improved sealability, long termdependability and reduced manufacturing costs. In a second embodiment ofthe invention, there is described an endform tubular assembly havingimproved properties for use in a fluid flow assembly for conveying fluidin a hydraulic system such as a power steering system, power brakesystem, air conditioner system, oil cooler system, various heatingsystems, and the like. In a third embodiment of the invention, a methodis described for the non-destructive evaluation of the endform tubularassemblies to determine the robustness of the assemblies during theendforming process. The evaluation of the assemblies is quickly andreliably performed by making a simple measurement on at least oneinherent feature of the assembly. This third embodiment will bediscussed more fully below.

In accordance with the first embodiment of the invention, a method forendforming a tubular member to provide an endform tubular assembly for ahydraulic system is as follows:

(a) providing a tubular member having a substantially uniform diameterand wall thickness, said tubular member capable of being endformed;

(b) reducing one end of the tubular member in a first station of aforming machine to provide a tubular member having a first tubularportion and a reduced second tubular portion;

(c) providing a connector member having an outer surface and an innersurface wherein the inner surface extends longitudinally through theconnector member which includes:

-   -   (1) a first shoulder segment defining a distal end of the        connector member, wherein the first shoulder segment including        at least one fixing member integral with the first shoulder        segment;    -   (2) a second shoulder segment defining a proximal end of the        connector member; and    -   (3) a brim segment intermediate the first and second shoulder        segments extending perpendicularly from the outer surface of the        connector member; wherein said first shoulder segment comprises        a first inner wall portion having a first inner surface        exhibiting a first diameter; the second shoulder segment        comprising a second inner wall portion having a second inner        surface exhibiting a second diameter and a third inner wall        portion having a third inner surface exhibiting a third        diameter, wherein the second diameter is smaller than said first        diameter, and the third diameter is larger than said second        diameter, but may be smaller than the first diameter;

(d) inserting the tubular member into the connector member such that thefirst tubular portion of the tubular member and the second tubularportion of the tubular member mate with the first inner wall portion ofthe connector member and the second wall portion of the connectormember, respectively;

(e) forming a uniform bead around the outer surface of the first tubularportion of the tubular member in a second station of the formingmachine, wherein the uniform bead is in the first shoulder segment ofthe connector member adjacent the brim segment to prevent longitudinalmovement of the tubular member in the connector member;

(f) expanding a proximal end of the second inner wall portion of thesecond tubular portion into the third inner wall portion of the secondshoulder segment, in a third station of the forming machine to providean endform tubular assembly wherein the tubular member has a first innerwall portion exhibiting a first diameter, a second inner wall portionexhibiting a second diameter and a third inner wall portion exhibiting athird diameter, the third inner wall portion defining a gauge diameterdepth in the proximal end of said endform tubular assembly.

Preferably, the endform tubular assembly is employed as at least one ofa first tubular assembly and a second tubular assembly in a fluid flowassembly for a power steering system, wherein the fluid flow assemblycomprises a housing having a steering gear disposed therein, the housingincluding a first port extending from an outer surface of the housing toan inner surface of the housing and a second port extending from theouter surface of the housing to the inner surface of the housing; apump; a first endform tubular assembly having a first end connected tothe first port in the housing and a second end attached to the pump,wherein the first endform tubular assembly conveys fluid under pressurefrom said pump to the housing through the first port; a second tubularassembly having a first end connected to the second port in the housingand a second end connected to the pump, wherein the second tubularassembly conveys fluid from the housing to the pump; and a clamp platehaving a first aperture through which the first tubular assemblyextends, a U-shaped second aperture through which the second tubularassembly extends, and a third aperture configured for connecting theclamp plate to the hydraulic housing, wherein the first port forreceiving the first tubular assembly and the second port for receivingthe second tubular assembly are configured, respectively to receive thefirst tubular assembly and the second tubular assembly such that theclamp plate fits flush against the housing.

In accordance with a second embodiment of the invention, a method forassembling an endform tubular assembly for use in a fluid flow assemblyis described as follows:

(a) providing a tubular member having a substantially uniform diameterand wall thickness, wherein the tubular member is capable of beingendformed;

(b) reducing one end of the tubular member in a first station of aforming machine to provide a tubular member having a first tubularportion and a reduced second tubular portion, the first tubular portionhaving a first diameter, and the reduced second tubular portion having asecond diameter;

(c) providing a connector member having an outer surface and an innersurface wherein the inner surface extends longitudinally through theconnector member, the connector member comprising:

-   -   (1) a first shoulder segment defining a distal end of the        connector member, the first shoulder portion including at least        one fixing member integral with the first shoulder portion;    -   (2) a second shoulder segment defining a proximal end of the        connector member; and    -   (3) a brim segment intermediate said first shoulder segment and        the second shoulder segment, the brim segment extending        perpendicularly from the outer surface of the connector member;        wherein the first shoulder segment comprises a first inner wall        portion having a first inner surface exhibiting a first        diameter; the second shoulder segment comprising a second inner        wall portion having a second inner surface exhibiting a second        diameter and a third inner wall portion having a third inner        surface exhibiting a third diameter, wherein the second diameter        is smaller than the first diameter, and the third diameter is        larger than said second diameter, but may be smaller than the        first diameter;

(d) inserting the tubular member into the connector member such that thefirst tubular portion of the tubular member and the second tubularportion of the tubular member mate with the first inner wall portion ofthe connector member and the second wall portion of the connectormember, respectively;

(e) forming a uniform bead around the outer surface of the first tubularportion of the tubular member in a second station of the formingmachine, wherein the uniform bead is in the first shoulder segment ofthe connector member adjacent the brim segment to prevent longitudinalmovement of the tubular member in the connector member;

(f) expanding a proximal end of the second inner wall portion of thesecond tubular portion into the third inner wall portion of the secondshoulder segment, in a third station of said forming machine to providea tubular member having a first inner wall portion, a second inner wallportion and a third inner wall portion, the reduced second outerdiameter having a second inner diameter and a third inner diameter, thethird inner wall portion defining a gauge diameter depth in the proximalend of the endform tubular member;

(g) providing a clamp plate having a substantially flat first surfaceand a substantially flat second surface wherein the second surfacecorresponds to the first surface; a first aperture configured to acceptthe distal end of the connector portion; a U-shaped second apertureconfigured to accept a distal end of a second tubular assembly and athird aperture for accepting a fastener for connecting the fluid flowassembly to the power steering housing;

(h) installing the first tubular assembly onto the clamp plate such thatthe aperture in the clamp plate receives the first shoulder segment ofthe connector member to provide a press fit coupling, wherein the clampplate abuts the brim segment of the connector member;

(i) installing the second tubular assembly onto the clamp plate suchthat the U-shaped second aperture receives the second tubular assemblysecuring the second tubular assembly thereto;

(j) installing the clamp plate assembly to the power steering housingemploying a single fastener wherein the first endform tubular assemblyengages a first port in the hydraulic housing for receiving pressurizedfluid from the pump, and the second tubular assembly engages a secondport in the power steering housing for returning the fluid from thehousing to the pump; wherein the clamp plate having the first endformtubular assembly and the second tubular assembly secured theretoprovides a clamp plate assembly;

(k) installing a sealing means on the outer surface of the proximal endof the endform tubular member adjacent the proximal end of the secondshoulder segment; and

(l) flaring the proximal end of the endform tubular member to retain theo-ring thereon. The fluid flow system comprises a housing for a steeringgear, the housing including a first port extending from an outer surfaceof the housing to an inner surface of the housing and a second portextending from the outer surface of the housing to an inner surface ofthe housing; a pump; a first tubular assembly having a first endconnected to the first port in the housing and a second end attached tothe pump, wherein the first tubular assembly conveys fluid underpressure from the pump to the housing; a second tubular assembly havinga first end connected to the second port in the housing and a second endconnected to the pump wherein the second tubular assembly conveys fluidfrom the housing to the pump; and a clamp plate having a first aperturethrough which the first tubular assembly extends, a U-shaped secondaperture having an open end through which the second tubular assemblyextends, and a third aperture intermediate the first aperture and saidsecond U-shaped aperture, the third aperture configured for connectingthe clamp plate to the hydraulic housing, wherein the first port forreceiving the first tubular assembly and the second port for receivingthe second tubular assembly are configured to receive the first tubularassembly and the second tubular assembly such that the clamp plate fitsflush against the housing.

Referring now to the drawings, FIGS. 1 and 2 are provided solely to showthe state of the prior art as it relates to fluid flow assemblies forpower steering systems. FIG. 1 shows a prior art power steering assembly10, which includes a pump 12, a steering gear 14, a first hose assembly16 for conveying pressurized fluid from the pump to the steering gear,and a second hose assembly 18 for returning fluid to the pump. FIG. 2shows a sectional view of a portion of the prior art assembly of FIG. 1wherein the first hose assembly 16 employs two spaced beads 22, 24 tosecure the hose to a bracket 20. The second hose assembly 18 includes aconnector 28 having a pair of spaced circumferential flanges forreceiving the bracket between the circumferential flanges therebysecuring the hose to the bracket.

FIGS. 3 through 5 illustrate an endform tubular assembly 100 including aclamp plate 162 in accordance with the present invention. As illustratedin FIG. 3 a connector member 102 includes a first shoulder portion 104including at least one fixing member 124 integral therewith; a secondshoulder portion 106 defining a proximal end of the connector member102, and a brim portion 108 intermediate the first shoulder portion 104and the second shoulder portion 106, the brim portion 108 extendingperpendicularly relative to the first and second shoulder portions,wherein the connector member 102 has an inner wall surface extendinglongitudinally through the connector member 102, the inner wall furthercomprising a first inner wall portion 110 having a first diameter, asecond inner wall portion 114 having a second diameter, and a thirdinner wall portion 118 having a third diameter, wherein the seconddiameter is smaller than both the first diameter and the third diameter,and the third diameter is larger than the second diameter, but may beeither larger or smaller than the first diameter In a preferred aspectof the invention, the frusto-conical angle defining the reduction of theinner surface of the first shoulder portion relative to the innersurface of the second shoulder portion is greater than 0° and less thanabout 90°. Preferably, the angle is about 30° to about 60°. Mostpreferably the angle will be about 400 to about 50°.

As illustrated in FIG. 4, an endform tubular assembly generallydesignated 100 includes a connector member 102 having a first shoulderportion 104 defining a distal end of the connector member 102. The firstshoulder portion 104 further includes at least one fixing member 124integral with the distal end of the first shoulder portion 104. Thefixing member may be of any configuration suitable to engage the beadand prevent axial movement of the tubular member in the connectormember. Typically, the fixing member is a tabular member extending fromthe distal end of the first shoulder portion of the connector member.The number of fixing members employed is not critical and may range froma single fixing member to several fixing members. Furthermore, when morethan one fixing member is employed, such fixing members may have thesame or different configuration. The fixing member may be in the form ofone or more tabs, projections, notches, indentations, grooves, ridges,etc. The bead 126 is not only an essential feature of the invention forpreventing both axial rotation and longitudinal movement of the tubularassembly relative to the connector member, but the proper formation ofthe bead indicates that a correct length of tubing was employed in thestep of forming the bead in the tubular assembly. As further illustratedin FIG. 4, a second shoulder portion 106 defines a proximal end of theconnector member 102. A brim portion 108 extends perpendicularlyrelative to the first and second shoulder portions 102, 103 andintermediate the two shoulder portions 102, 103.

The endform tubular member 128 includes an intermediate portion 170 thathas an outer surface corresponding to the inner wall surface of theconnector member 102 such that the outer surface of the endform tubularmember fixedly engages the inner wall surface of the connector member102. A distal portion of the endform tubular member 128 has an innersurface and an outer surface, the distal portion extending axially fromthe intermediate portion. The distal portion has a bead 126 formedtherein adjacent the first shoulder portion 104 of the connector member102. The bead 126 prevents the longitudinal movement of the endformtubular member 128 in the connector member 102 and also fixedly engagesthe fixing member(s) 124 in the first shoulder portion 104 to preventaxial rotation of the endform tubular member 128 relative to theconnector member 102. The endform tubular member 128 further includes aproximal portion having an inner surface and an outer surface. Theproximal portion of the second shoulder portion 106 having an innersurface and an outer surface. The second shoulder portion 106 includesan annular ridge 118 formed in the proximal end thereof. The endformtubular member 128 is extending from the proximal end of the connectormember 102 is expanded into the notch simultaneously with the formationof the bead in the endform tubular assembly. The expansion of thetubular member 128 into the annular ridge in the proximal end of thesecond shoulder portion 106 creates a cylindrical area therein, thelongitudinal length 178 of which defines a gauge diameter depth 122. Thegauge diameter depth 122 not only provides additional means forpreventing movement of the endform tubular member 128 relative to theconnector member 102, but the longitudinal length of the gauge diameterdepth 122 is a direct correlation of material flow into the ridge 118formed in the proximal end of the first shoulder portion 104.

FIG. 5 schematically illustrates a hydraulic housing 156 having a port158 for accepting the endform tubular assembly 100. Typically, the port158 may exhibit a slight annular taper to help squeeze the o-ring duringinsertion to provide a secure seal. The port 158 includes a recessedportion 160 sized to accept the brim 108 of the connector member. Therecessed portion 160 allows the flat surface of the clamp plate 162 tofit flush against the housing. The flush fit of the clamp plate againstthe housing prevents the clamp plate from being deformed in instanceswhere excessive torque may be unwittingly placed on the single fitting.Such deformation of the clamp plate would not only destroy the clampplate, but almost certainly would cause irreparable damage to thetubular assemblies and perhaps even to the hydraulic housing port and/orthe housing itself.

FIG. 6 is an elevated plan view of the clamp plate 162. The clamp plate162 includes a first aperture 172 sized to accept the first shoulderportion of the connector member wherein the connector member 105 and theclamp plate 162 are secured together, preferably by press fitting theclamp plate 162 onto the first shoulder portion of the connector member.A U-shaped notch 174 on the other end of the clamp plate from the firstaperture is configured to accept and secure a return tubular member inthe clamp plate 162. A second aperture 176 intermediate the firstaperture 172 and the U-shaped notch 174, is sized to receive a fastenersuch as a bolt, screw, pin, or equivalent for mounting the clamp plate162 including both of the fluid flow assemblies to the hydraulic housingin one mounting step by applying an appropriate torque to a singlefastener.

The prior art, an o-ring is employed In within an annular groove in theproximal end of the tube or in the proximal end of a connector to sealthe structure and prevent leaks. The formation of such groove requiresadditional labor and expense. The sealing member of the presentinvention is simply placed onto the end of the endform tubular memberthat extends longitudinally through a connector member. According to thepresent invention, the sealing member simply rests against the end ofthe connector without requiring a separate groove. The proximal end ofthe tubular member is slightly flared to prevent the sealing member fromfalling off. The sealing member of the present invention is typically ano-ring and preferably an o-ring formed from a polymeric material such asnitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber,ethylene-acrylate elastomer, ethylene-vinyl acetate copolymer, acrylicrubber, ethylene methacrylate elastomer, tetrafluoroethylene, and blendsthereof. A retaining ring is preferably employed between the metal endof the second shoulder portion and the o-ring to help maintain theintegrity of the o-ring. The retaining ring is formed from a polymericmaterial such as Teflon (tetrafluoroethylene), metal or metal alloy. Ifthe retaining ring is formed from a metal, it is preferred that themetal be different and less rigid than the metal used to form theconnector member. Preferably, the retaining ring is a Teflon retainingring. In placing the retaining ring against the metal surface of thesecond shoulder portion of the connector member, it is important thatthe perpendicular surface of the connector member be as close to 90° aspossible to prevent any undo skewed pressure which may lead to prematurefailure of the retaining ring and/or o-ring.

The connector member and the endform tubular member are typically formedfrom a metal having sufficient characteristics to withstand the harshenvironment of an automotive vehicle motor compartment and the pressuresinvolved in conveying high pressure fluid. Preferably, both theconnector member and the endform tubular assembly are formed from steelor a material having steel as a major ingredient.

As discussed briefly above, certain inherent features present in theendform tubular assembly provides a quantified numerical value which,when compared to a predetermined range of quantified numerical values,is a valuable method for assessing the robustness of the resultantendform tubular assembly and for predicting the performance of theendform tubular assembly in high pressure applications over prolongedperiods of time.

It is to be understood that the tubular member used in forming theendform tubular assembly of the invention can be of any size necessaryto perform the particular function desired providing, of course, thatthe connector member is sized accordingly. Preferably the tubular memberhas an outer diameter of about 5/16 inch to about ½ inch. A tubularmember having an outer diameter of about ⅜ inch has been found to bedesirable.

In a first significant aspect of the invention, it has been found thatan accurate measurement of the diameter 180 of bead 126 formed in theendform tubular member 128 at the distal end of the first shoulderportion 104 is a direct indicator as to the reliability of the endformtubular assembly 100 in high pressure applications. When the diameter180 of the bead 126 is within a specifically determined range of values,the endform tubular assembly 100 can be expected to perform reliablyover a prolonged period of time in high pressure applications. When themeasured diameter 180 of the bead 126 is at or near the extreme ends ofthe predetermined range of values, the robustness of the endform tubularassembly predictably becomes somewhat less reliable. Generally, if thediameter 180 falls outside the predetermined range, the endform tubularassembly is discarded. The diameter of the bead can be measured be anymeans available which will provide an accurate measurement of the bead.It has been found that calipers and an optical comparative, both ofwhich are commercially available, easily and accurately provide therequired measurements.

In a second significant aspect of the invention, it has been found thatan accurate measurement of the length 178 of the inner surface definedas the gage diameter depth is a direct indicator as to the reliabilityof the endform tubular assembly 100 in high pressure applications. Whenthe length 178 of the gage diameter depth 122 is within a specificallydetermined range of values, the endform tubular assembly 100 can beexpected to perform reliably over a prolonged period of time in highpressure applications. Much like the measurement of the bead diameterdiscussed above, when the length of the gage diameter depth 122 fallswithin a specifically determined range of values, the endform tubularassembly can be expected to perform reliably over a prolonged period oftime in high pressure applications. As the measured length 178 of thegage diameter depth 122 is at or near the extreme ends of thepredetermined range of values, the robustness of the endform tubularassembly predictably becomes somewhat less reliable. Generally, if thelength 178 falls outside the predetermined range, the endform tubularassembly 100 is discarded. The accurate measurement of the length of thegage diameter depth compared to a predetermined length is a reliableindication of the robustness of the endform tubular assembly. Thelongitudinal length (or depth) of the gauge diameter depth can bemeasured be any means available which will provide an accuratemeasurement of the longitudinal length of the gauge diameter depth. Ithas been found that a simple device such as a pin inserted into theinner diameter of the tube at the gauge diameter depth will easily andaccurately provide the required measurements. If the pin reaches apredetermined depth, the tube is satisfactory.

Prior to the present invention, there were no non-destructive methodsfor determining the reliability of such tubular assembly parts. Moreimportantly, there is no current method for determining whether aparticular tubular assembly passes or fails predetermined specificationsAccordingly, manufacturers randomly select one or more of the tubularassemblies, cut them open to visually determine the robustness of theselected tubular assemblies, and then adjusts the manufacturing processaccordingly. Obviously, the inspected tubular assemblies are destroyedand have to be discarded. Such determinations are inefficient, timeconsuming, and unreliable at best. The diameter of said bead compared toa predetermined diameter is a reliable indication of the robustness ofsaid endform tubular assembly, during the manufacture of such tubularassemblies.

1. A method for endforming a tubular member to provide an endformtubular: assembly for a hydraulic system, said method comprising: (a)providing a tubular member having a substantially uniform diameter andwall thickness, said tubular member capable of being endformed; (b)reducing one end of said tubular member in a first station of a formingmachine to provide a tubular member having a first tubular portion and areduced second tubular portion; (c) providing a connector member havingan outer surface and an inner surface wherein said inner surface extendslongitudinally through said connector member, said connector membercomprising: (1) a first shoulder segment defining a distal end of saidconnector member, said first shoulder segment including at least onefixing member integral with said first shoulder segment; (2) a secondshoulder segment defining a proximal end of said connector member; and(3) a brim segment intermediate said first shoulder segment and saidsecond shoulder segment, said brim segment extending perpendicularlyfrom said outer surface of said connector member; wherein said firstshoulder segment comprises a first inner wall portion having a firstinner surface exhibiting a first diameter; said second shoulder segmentcomprising a second inner wall portion having a second inner surfaceexhibiting a second diameter and a third inner wall portion having athird inner surface exhibiting a third diameter, wherein said seconddiameter is smaller than said first diameter, and said third diameter islarger than said second diameter; (d) inserting said tubular member intosaid connector member such that said first tubular portion of saidtubular member and said second tubular portion of said tubular membermate with said first inner wall portion of said connector member andsaid second wall portion of said connector member, respectively; (e)forming a uniform bead around said outer surface of said first tubularportion of said tubular member in a second station of said formingmachine, wherein said uniform bead is in said first shoulder segment ofsaid connector member adjacent said brim segment to prevent longitudinalmovement of said tubular member in said connector member; and (f)expanding a proximal end of said second inner wall portion of saidsecond tubular portion into said third inner wall portion of said secondshoulder segment, in a third station of said forming machine to providean endform tubular assembly wherein said tubular member has a firstinner wall portion exhibiting a first diameter, a second inner wallportion exhibiting a second diameter and a third inner wall portionexhibiting a third diameter, said third inner wall portion defining agauge diameter depth in said proximal end of said endform tubularassembly.
 2. The method of claim 1 further comprising installing asealing member on said outer surface of said proximal portion of saidendform tubular member, said sealing member configured to mate with saidhydraulic housing to seal said endform tubular member to said hydraulichousing.
 3. The method of claim 2 wherein said sealing member includesan o-ring disposed on said outer surface of said proximal end of saidendform tubular assembly.
 4. The method of claim 3 wherein said o-ringis formed from a polymeric material selected from the group consistingof nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber,ethylene-acrylate elastomer, ethylene-vinyl acetate copolymer, acrylicrubber, ethylene methacrylate elastomer, tetrafluoroethylene, and blendsthereof.
 5. The method of claim 3 wherein said proximal end of saidendform tubular assembly is flared to retain said o-ring thereon.
 6. Themethod of claim 3 further including a retaining ring between said o-ringand said second shoulder portion of said connector member, saidretaining ring having sufficient resilience to prevent deformation ofsaid o-ring.
 7. The method of claim 6 wherein said retaining ring isformed from a polymeric material, a metal or a metal alloy.
 8. Themethod of claim 7 wherein said retaining ring is apolytetrafluoroethylene ring.
 9. The method of claim 1 wherein saidsecond inner wall portion having a reduced diameter compared to saiddiameter of said first inner wall portion exhibits an inner concentricreduction angle of up to about 90°.
 10. The method of claim 9 whereinsaid second inner wall portion having a reduced diameter compared tosaid diameter of said first inner wall portion exhibits an innerconcentric reduction angle of about 15° to about 60°.
 11. The method ofclaim 1 wherein said endform tubular assembly is employed as at leastone of a first tubular assembly and a second tubular assembly in a fluidflow assembly for a power steering system, wherein said fluid flowassembly comprises a housing having a steering gear disposed therein,said housing including a first port extending from an outer surface ofsaid housing to an inner surface of said housing and a second portextending from said outer surface of said housing to said inner surfaceof said housing; a pump; a first endform tubular assembly having a firstend connected to said first port in said housing and a second endattached to said pump, wherein said first endform tubular assemblyconveys fluid under pressure from said pump to said housing through saidfirst port; a second tubular assembly having a first end connected tosaid second port in said housing and a second end connected to saidpump, wherein said second tubular assembly conveys fluid from saidhousing to said pump; and a clamp plate having a first aperture throughwhich said first tubular assembly extends, a U-shaped second aperturethrough which said second tubular assembly extends, and a third apertureconfigured for connecting said clamp plate to said hydraulic housing,wherein said first port for receiving said first tubular assembly andsaid second port for receiving said second tubular assembly areconfigured, respectively to receive said first tubular assembly and saidsecond tubular assembly such that said clamp plate fits flush againstsaid housing.
 12. The method of claim 1 wherein said step (e) forming auniform bead around said outer surface of said first tubular portion ofsaid tubular member, and said step (f) expanding a proximal end of saidsecond inner wall portion of said second tubular portion into said thirdinner wall portion of said second shoulder segment, are formedsimultaneously in a second station of said forming machine.
 13. A methodfor assembling an endform tubular assembly in a fluid flow assembly fora power steering system, wherein said fluid flow system comprises ahousing for a steering gear, said housing including a first portextending from an outer surface of said housing to an inner surface ofsaid housing and a second port extending from said outer surface of saidhousing to an inner surface of said housing; a pump; a first tubularassembly having a first end connected to said first port in said housingand a second end attached to said pump, wherein said first tubularassembly conveys fluid under pressure from said pump to said housing; asecond tubular assembly having a first end connected to said second portin said housing and a second end connected to said pump wherein saidsecond tubular assembly conveys fluid from said housing to said pump;and a clamp plate having a first aperture through which said firsttubular assembly extends, a U-shaped second aperture having an open endthrough which said second tubular assembly extends, and a third apertureintermediate said first aperture and said second U-shaped aperture, saidthird aperture configured for connecting said clamp plate to saidhydraulic housing, wherein said first port for receiving said firsttubular assembly and said second port for receiving said second tubularassembly are configured to receive said first tubular assembly and saidsecond tubular assembly such that said clamp plate fits flush againstsaid housing, said method comprising: (a) providing a tubular memberhaving a substantially uniform diameter and wall thickness, said tubularmember capable of being endformed; (b) reducing one end of said tubularmember in a first station of a forming machine to provide a tubularmember having a first tubular portion and a reduced second tubularportion, said first tubular portion having a first diameter, and saidreduced second tubular portion having a second diameter; (c) providing aconnector member having an outer surface and an inner surface whereinsaid inner surface extends longitudinally through said connector member,said connector member comprising: (1) a first shoulder segment defininga distal end of said connector member, said first shoulder portionincluding at least one fixing member integral with said first shoulderportion; (2) a second shoulder segment defining a proximal end of saidconnector member; and (3) a brim segment intermediate said firstshoulder segment and said second shoulder segment, said brim segmentextending perpendicularly from said outer surface of said connectormember; wherein said first shoulder segment comprises a first inner wallportion having a first inner surface exhibiting a first diameter; saidsecond shoulder segment comprising a second inner wall portion having asecond inner surface exhibiting a second diameter and a third inner wallportion having a third inner surface exhibiting a third diameter,wherein said second diameter is smaller than said first diameter, andsaid third diameter is larger than said second diameter; (d) insertingsaid tubular member into said connector member such that said firsttubular portion of said tubular member and said second tubular portionof said tubular member mate with said first inner wall portion of saidconnector member and said second wall portion of said connector member,respectively; (e) forming a uniform bead around said outer surface ofsaid first tubular portion of said tubular member in a second station ofsaid forming machine, wherein said uniform bead is in said firstshoulder segment of said connector member adjacent said brim segment toprevent longitudinal movement of said tubular member in said connectormember; (f) expanding a proximal end of said second inner wall portionof said second tubular portion into said third inner wall portion ofsaid second shoulder segment, in a third station of said forming machineto provide a tubular member having a first inner wall portion, a secondinner wall portion and a third inner wall portion, said reduced secondouter diameter having a second inner diameter and a third innerdiameter, said third inner wall portion defining a gauge diameter depthin said proximal end of said endform tubular member. (g) providing aclamp plate having a substantially flat first surface and asubstantially flat second surface wherein said second surfacecorresponds to said first surface; a first aperture configured to acceptsaid distal end of said connector portion; a U-shaped second apertureconfigured to accept a distal end of a second tubular assembly and athird aperture for accepting a fastener for connecting said fluid flowassembly to said power steering housing; (h) installing said firsttubular assembly onto said clamp plate such that said aperture in saidclamp plate receives said first shoulder segment of said connectormember to provide a press fit coupling, wherein said clamp plate abutssaid brim segment of said connector member; (i) installing said secondtubular assembly onto said clamp plate such that said U-shaped secondaperture receives said second tubular assembly securing said secondtubular assembly thereto; (j) installing said clamp plate assembly tosaid power steering housing employing a single fastener wherein saidfirst endform tubular assembly engages a first port in said hydraulichousing for receiving pressurized fluid from said pump, and said secondtubular assembly engages a second port in said power steering housingfor returning said fluid from said housing to said pump; Wherein saidclamp plate having said first endform tubular assembly and said secondtubular assembly secured thereto provides a clamp plate assembly; (k)installing a sealing means on said outer surface of said proximal end ofsaid endform tubular member adjacent said proximal end of said secondshoulder segment; and (l) flaring said proximal end of said endformtubular member to retain said o-ring thereon.
 14. The method of claim 13wherein said second inner wall portion having a smaller diametercompared to said diameter of said first inner wall portion exhibits aninner concentric reduction angle up to about 90°.
 15. The method ofclaim 14 wherein said second inner wall portion having a reduceddiameter compared to said diameter of said first inner wall portionexhibits an inner concentric reduction angle of about 15° to about 60°.16. The method of claim 13, wherein said second shoulder segment of saidconnector member has a perpendicular end exhibiting an angle of about90° with respect to said outer surface of said proximal end of saidendform tubular fitting assembly.
 17. The method of claim 13, whereinsaid connector member is metal or metal alloy.
 18. The method of claim13, wherein said endform tubular member is metal or metal alloy.
 19. Themethod of claim 13 wherein said at least one fixing member is anon-uniform surface.
 20. The method of claim 19 wherein said non-uniformsurface is one or more projections, indentations, grooves, ridges orcombinations thereof.
 21. The method of claim 13 wherein said step (e)forming a uniform bead around said outer surface of said first tubularportion of said tubular member, and said step (f) expanding a proximalend of said second inner wall portion of said second tubular portioninto said third inner wall portion of said second shoulder segment, areformed simultaneously in a second station of said forming machine. 22.In a method for the assembly of a fluid flow assembly in a powersteering system wherein first and second tubular members are mountedonto a bracket and the assembly is simultaneously secured to a steeringgear, the improvement comprising: (a) providing a tubular member havinga substantially uniform diameter and wall thickness, said tubular membercapable of being endformed; (b) reducing one end of said tubular memberin a first station of a forming machine to provide a tubular memberhaving a first tubular portion and a reduced second tubular portion,said first tubular portion having a first diameter, and said reducedsecond tubular portion having a second diameter; (c) providing aconnector member having an outer surface and an inner surface whereinsaid inner surface extends longitudinally through said connector member,said connector member comprising: (1) a first shoulder segment defininga distal end of said connector member, said first shoulder portionincluding at least one fixing member integral with said first shoulderportion; (2) a second shoulder segment defining a proximal end of saidconnector member; and (3) a brim segment intermediate said firstshoulder segment and said second shoulder segment, said brim segmentextending perpendicularly from said outer surface of said connectormember; wherein said first shoulder segment comprises a first inner wallportion having a first inner surface exhibiting a first diameter; saidsecond shoulder segment comprising a second inner wall portion having asecond inner surface exhibiting a second diameter and a third inner wallportion having a third inner surface exhibiting a third diameter,wherein said second diameter is smaller than said first diameter, andsaid third diameter is larger than said second diameter; (d) insertingsaid tubular member into said connector member such that said firsttubular portion of said tubular member and said second tubular portionof said tubular member mate with said first inner wall portion of saidconnector member and said second wall portion of said connector member,respectively; (e) forming a uniform bead around said outer surface ofsaid first tubular portion of said tubular member in a second station ofsaid forming machine, wherein said uniform bead is in said firstshoulder segment of said connector member adjacent said brim segment toprevent longitudinal movement of said tubular member in said connectormember; (f) expanding a proximal end of said second inner wall portionof said second tubular portion into said third inner wall portion ofsaid second shoulder segment, in a third-station of said forming machineto provide a tubular member having a first inner wall portion, a secondinner wall portion and a third inner wall portion, said reduced secondouter diameter having a second inner diameter and a third innerdiameter, said third inner wall portion defining a gauge diameter depthin said proximal end of said endform tubular member; (g) installing aretaining ring on said outer surface of said proximal end of saidendform tubular member adjacent said proximal end of said secondshoulder segment; (h) installing an o-ring on said outer surface of saidproximal portion of said endform tubular fitting member, said o-ringconfigured to mate with said housing to seal said endform tubularfitting member to said housing; (i) flaring said proximal end of saidendform tubular fitting assembly to retain said o-ring thereon; (j)providing a clamp plate having a substantially flat first surface and asubstantially flat second surface wherein said second surfacecorresponds to said first surface; a first aperture configured to acceptsaid distal end of said connector portion; a U-shaped second apertureconfigured to accept a distal end of a second tubular assembly and athird aperture for accepting a fastener for connecting said fluid flowassembly to said power steering housing; (k) installing said firsttubular assembly onto said clamp plate such that said aperture in saidclamp plate receives said first shoulder segment of said connectormember to provide a press fit coupling, wherein said clamp plate abutssaid brim segment of said connector member; (l) installing a secondtubular assembly onto said clamp plate such that said U-shaped secondaperture receives said second tubular assembly securing said secondtubular assembly thereto; and (m) installing said clamp plate assemblyto said power steering housing employing a single fastener wherein saidfirst endform tubular assembly engages a first port in said hydraulichousing for receiving pressurized fluid from said pump, and said secondtubular assembly engages a second port in said hydraulic housing forreturning said fluid from said housing to said pump; wherein said clampplate having said first endform tubular assembly and said second tubularassembly secured thereto provides a clamp plate assembly.
 23. The fluidflow assembly of claim 22 wherein said second inner wall portion has areduced diameter compared to said diameter of said first inner wallportion.
 24. The method of claim 23 wherein said second inner wallportion having a reduced diameter compared to said diameter of saidfirst inner wall portion exhibits an inner concentric reduction angle upto about 90°.
 25. The method of claim 24 wherein said second inner wallportion having a reduced diameter compared to said diameter of saidfirst inner wall portion exhibits an inner concentric reduction angle ofabout 15° to about 60°.
 26. The method of claim 22 wherein said o-ringis formed from a polymeric material selected from the group consistingof nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber,ethylene-acrylate elastomer, ethylene-vinyl acetate copolymer, acrylicrubber, ethylene methacrylate elastomer, and blends thereof.
 27. Themethod of claim 26 wherein said retaining ring is formed from apolymeric material, a metal or a metal alloy.
 28. The method of claim 27wherein said retaining ring is a tetrafluoroethylene ring.
 29. Themethod of claim 22, wherein said connector member is metal or metalalloy.
 30. The method of claim 22, wherein said endform tubular memberis metal or metal alloy.
 31. The method of claim 22 wherein said atleast one fixing member is a non-uniform surface.
 32. The method ofclaim 31 wherein said non-uniform surface is one or more projections,indentations, grooves, ridges or combinations thereof.
 32. The method ofclaim 22 wherein said step (e) forming a uniform bead around said outersurface of said first tubular portion of said tubular member, and saidstep (f) expanding a proximal end of said second inner wall portion ofsaid second tubular portion into said third inner wall portion of saidsecond shoulder segment, are formed simultaneously in a second stationof said forming machine.